Method for manufacturing non-oriented electrical steel sheet having high magnetic flux density

Abstract

A quench solidification method, wherein a steel cast strip having a mean grain size 50 μm or more is prepared and then the steel cast strip is rolled to produce a non-oriented electrical steel sheet having high magnetic flux density in both L and C directions. However the magnetic flux density reduces when the cold reduction rate exceeds 70%. To avoid this problem the non-oriented electrical steel sheet is manufactured with a ratio of at least 4 of the integrated intensity of the {100} plane for a given sample of steel to the integrated intensity of {100} plane for a “random” sample in which crystal grains have random orientations; and a cold reduction rate of the cold-rolling is between 70% and 85%. The superheating degree of the molten steel can be 70° C. or more.

1. A method for manufacturing non-oriented electrical steel sheet having high magnetic flux density comprising the steps of:
 preparing a molten steel comprising, in mass %, up to 0.008% of C, 1.8% to 7% of (Si+2Al), 0.02 to 1.0% of Mn, up to 0.005% of S, up to 0.01% of N, and the balance Fe and unavoidable impurities; 
 solidifying the molten steel on at least one moving cooling wall to form a steel cast strip; 
 cold-rolling the steel cast strip to a predetermined thickness; and 
 annealing the cold-rolled steel; 
 wherein {100} pole intensity is at least 4; and a cold reduction rate of the cold-rolling is between 70% and 85%. 
 
     
     
       2. A method for manufacturing non-oriented electrical steel sheet having high magnetic flux density comprising the steps of:
 preparing a molten steel comprising, in mass %, up to 0.008% of C, 1.8% to 7% of (Si+2Al), 0.02 to 1.0% of Mn, up to 0.005% of S, up to 0.01% of N, and the balance Fe and unavoidable impurities; 
 solidifying the molten steel on a at least one moving cooling wall to form a steel cast strip; 
 cold-rolling the steel cast strip to a predetermined thickness; and 
 annealing the cold-rolled steel; 
 wherein a cold reduction rate of the cold-rolling is between 70% and 85%; and wherein a superheating degree of the molten steel immediately before being solidified is at least 70° C. 
 
     
     
       3. The method according to  claim 1 , wherein a superheating degree of the molten steel immediately before being solidified is 70° C. to 100° C. 
     
     
       4. The method according to  claim 1 , wherein the molten steel comprises, in mass %, 0.0011–0.0013% of C. 
     
     
       5. The method according to  claim 1 , wherein the cold rolling is performed at a temperature of at least 180° C. 
     
     
       6. The method according to  claim 2 , wherein the cold rolling is performed at a temperature of at least 180° C. 
     
     
       7. The method according to  claim 5 , wherein the cold rolling is performed at a temperature of 180 to 350° C. 
     
     
       8. The method according to  claim 6 , wherein the cold rolling is performed at a temperature of 180 to 350° C. 
     
     
       9. The method according to  claim 1 , wherein the {100} pole intensity is 4 to 6.4. 
     
     
       10. The method according to  claim 1 , wherein the cold-rolled steel has columnar crystals. 
     
     
       11. The method according to  claim 1 , wherein the cold-rolled steel has a greater number of columnar crystals than spherical equiaxial crystals. 
     
     
       12. The method according to  claim 1 , wherein the molten steel is solidified using the single roll method. 
     
     
       13. The method according to  claim 1 , wherein the molten steel is solidified using the twin roll method. 
     
     
       14. The method according to  claim 2 , wherein the molten steel comprises, in mass %, 0.0011–0.0013% of C. 
     
     
       15. The method according to  claim 2 , wherein the {100} pole intensity is 4 to 6.4. 
     
     
       16. The method according to  claim 2 , wherein the cold-rolled steel has columnar crystals. 
     
     
       17. The method according to  claim 2 , wherein the cold-rolled steel has a greater number of columnar crystals than spherical equiaxial crystals. 
     
     
       18. The method according to  claim 2 , wherein the {100} pole intensity is at least 4.